The present invention relates to rotary regenerative air preheaters which employ axial seals and axial seal plates located between the rotor and the rotor housing and dividing the air preheater into a gas sector and one or more air sectors. Specifically, the invention relates to a novel arrangement for mounting and adjusting the axial seal plates.
A rotary regenerative air preheater transfers sensible heat from the flue gas leaving a boiler to the entering combustion air through regenerative heat transfer surface in a rotor which turns continuously through the gas and air streams. The rotor which is packed with the heat transfer surface is supported through a lower bearing at the cold end of the air preheater and guided through a bearing assembly located at the top hot end. The rotor is divided into compartments by a number of radially extending plates referred to as diaphragms. These compartments are adapted to hold modular baskets in which the heat transfer surface is contained. The air preheater is divided into a flue gas side or sector and one or more combustion air sides or sectors by sector plates. Flexible radial seals on the rotor, usually mounted on the top and bottom edges of the diaphragms, are in close proximity to these sector plates and minimize leakage of gas and air between sectors. Likewise, axial seal plates are mounted on the housing between the housing and the periphery of the rotor between the air and gas sectors. These axial seal plates cooperate with flexible axial seals mounted on the outer ends of the diaphragms. These axial seals and seal plates together with the radial seals and sector plates effectively separate the air and flue gas streams from each other.
For maximum effectiveness, the axial sealing plates must be adjustable during operation to accommodate for thermal expansion and wear of parts. The prior art practice has been to use an arrangement of four adjusters, referred to as canister-type adjusters, which are each attached to the housing and to the axial seal plated, one in the proximity of each of the four corners of the axial seal plate and move the axial seal plate inward and outward in the radial direction. Each adjuster requires a mounting box or canister, several grade plates, a threaded and machined adjuster rod, shear bolt means to tie the adjuster rod to the axial seal plate plus an assortment of nuts and bolts. This is a somewhat expensive device primarily because of the cost to manufacture the adjustor rod. In addition, this adjuster is difficult to install and replace because it must be connected to both the housing and the axial seal plate and there is limited access available to the axial seal plate.